JP2002176372A - Radio communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide wide band radio communication equipment where bands are made wider while superior characteristics are given to respective circuit blocks and the whole bands can be inspected in shorter time. SOLUTION: Radio communication equipment has an antenna part where antennas are connected in parallel so that the characteristic impedance of the respective antennas, viewed from a common power feeding point, shows a minimum value and an amplifier 21 to which a reception signal from the antenna part is inputted and in which the input stage of the amplifier has a matching circuit 22 whose characteristic is varied by a control signal and the output stage of the amplifier has a wide band matching circuit 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication apparatus having a configuration capable of transmitting and receiving a signal of a relatively wide band and easily checking the use status of all channels.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a configuration of a conventional radio communication device. In FIG. 6, a high-frequency signal received by an antenna 101 reaches a receiving circuit block via a switch circuit 102. The switch circuit generally uses a semiconductor switch. The received high-frequency signal is a wideband band-limiting filter
At 103, unnecessary signals and noise components outside the band are removed, and only signals within the necessary frequency band are extracted.

Next, the received high-frequency signal is amplified by a low-noise amplifier 104 and input to a high-frequency signal terminal of a down-converter 105. Downconverter 105 outputs an intermediate frequency signal based on the input received high-frequency signal and the output signal of local signal oscillator 106. The intermediate frequency signal has a target signal near its center frequency, but also includes frequency components before and after it, such as an adjacent channel. Therefore, a non-target signal is removed by the narrow-band channel filter 107. . The intermediate frequency signal from which the signal other than the intended signal has been removed is input to the demodulator 108, and the intended demodulated signal such as an audio signal, an image signal, or a digital data signal can be correctly obtained.

On the other hand, a voice signal, image signal, digital data signal, or the like transmitted from a wireless communication device is modulated by a modulator 109, and a transmission high-frequency signal output from the modulator is amplified by a high power amplifier 110. Unwanted signals such as harmonic components are removed by a band-pass filter 111, passed through a switch circuit 102, and transmitted from an antenna 101.

[0005]

However, the wireless communication device according to the above-mentioned conventional configuration is suitable for operation in a relatively narrow frequency bandwidth. It is clear that there are various issues.

For example, an antenna circuit, a low-noise amplifier for a reception signal, a high-power amplifier for transmission, and the like must be a narrow-band circuit in order to obtain excellent characteristics in principle. In order to check the use status of the channel, there is a problem that much time is required for the wide band.

SUMMARY OF THE INVENTION In order to solve these problems, the present invention provides a radio communication device which has a wide band while having excellent characteristics for each circuit block, and which can check all bands in a shorter time. With the goal.

[0008]

According to the first aspect of the present invention,
An antenna unit connected in parallel so that the characteristic impedance of each antenna as viewed from the common feeding point exhibits a minimum value is provided at the initial stage of the communication device.

According to a second aspect of the present invention, an amplifier input stage to which a received signal is input is provided with a matching circuit whose characteristic is made variable by a control signal, and a wideband matching circuit is provided at an output stage of the amplifier. It is characterized by having.

According to a third aspect of the present invention, an input stage of an amplifier to which a received signal is input is provided with a plurality of band-pass filters having sequentially different center frequencies, and the filters are connected to the amplifier by a control signal. The connection is switched, and a broadband matching circuit is provided at an output stage of the amplifier.

According to a fourth aspect of the present invention, there is provided an antenna unit connected in parallel so that the characteristic impedance of each antenna as viewed from a common feeding point exhibits a minimum value, and an amplifier to which a reception signal from the antenna unit is input. The input stage of the amplifier is provided with a matching circuit whose characteristics are made variable by a control signal, and the output stage of the amplifier is provided with an amplifier having a broadband matching circuit.

According to a fifth aspect of the present invention, there is provided an antenna unit connected in parallel so that the characteristic impedance of each antenna as viewed from a common feeding point exhibits a minimum value, and an amplifier to which a reception signal from the antenna unit is input. The input stage of the amplifier is provided with a plurality of band-pass filters having sequentially different center frequencies, and the connection of the filter to the amplifier is switched by a control signal. And an amplifier having a circuit.

According to the above invention, each block of the wireless communication apparatus has excellent characteristics and has a wide band as a whole.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG.
(A), (b), (c) is a figure which shows the structure about the antenna part in 1st Embodiment of this invention, and characteristic impedance. In FIG. 1A, the narrow-band antenna elements 1 to 5 are all connected in parallel at a feeding point 6.

The characteristic impedance of the antenna element has a frequency dependence, and the frequency dependence is small near the resonance frequency where the reactance becomes zero when the impedance becomes the lowest, that is, when the impedance is represented by a complex number. It is easy to match with the circuit connected to the antenna element, and therefore the characteristics as a wireless communication device are also excellent, but when various characteristics such as radiation characteristics are pursued, the effective bandwidth generally becomes narrow. It is known.

FIG. 1B shows an antenna according to the present invention.
FIG. 3 is a diagram showing a relationship between characteristic impedances of antenna elements 1 to 5 and frequencies. The vertical axis represents the characteristic impedance value, and the horizontal axis represents the frequency. The characteristic impedance of each antenna element is at its resonance frequency f
It has become minimum at ₁ to f _5. The characteristic impedance on the antenna element side as viewed from the common feed point 6 is
The result is as shown in FIG. It operates as a broadband antenna to the bandwidth used by continuous frequency f ₁ to f _5.

(Second Embodiment) FIG. 2A,
(B), (c) is a figure which shows the wide band low noise amplifier in the 2nd Embodiment of this invention. FIG. 2 (a)
FIG. 2 is a block diagram illustrating a configuration of the amplifier. FIG. 2 (a)
, The amplification circuit AMP21 has an input-side matching circuit MN
22 and an output-side matching circuit MN23. Further, a control signal 24 is applied to the matching circuit 22 on the input side.

In general, when a low-noise amplifier is configured with only one amplifier element such as a transistor, the output-side matching circuit 23 is configured so that the gain of the amplifier is maximized, and the noise figure of the amplifier is minimized. The input-side matching circuit 22 is configured as described above. Here, the matching circuit 23 on the output side has a wide band in many cases, but the matching circuit 22 on the input side such that the noise figure of the amplifier is minimum does not match the matching condition at which the gain is maximum, that is, the narrow band and the matching condition are satisfied. There is no way to be.

Therefore, in the present invention, the matching circuit on the input side is used.
The operation of 22 is switched by the control signal 24, and an input matching circuit suitable for the frequency band to be used is selected. As a result, a low-noise amplifier in which the low-noise band is widened can be realized.

FIG. 2B is a block diagram showing an example of the configuration of a circuit suitable as the matching circuit 22 on the input side. FIG.
In (b), the input terminal 10 is a signal terminal on the antenna side,
The two capacitors 11 are capacitors for blocking DC and also for coupling high-frequency signals. The resistance element 13 is an element for inputting a control signal 24. The matching circuit 22 is composed of a band switching diode 14, a capacitor 15, an inductance 16, and an inductance 17.

The operation of the matching circuit 22 shown in FIG. 2B will be described. When the voltage of the control signal 24 is at the L level, the band switching diode 14 is in the off state, and the impedance when the terminal of the diode 14 and the control signal 24 is viewed from the inductance 16 and the inductance 17 is maximum. Therefore, if the value of the resistance element 13 is sufficiently large, the matching circuit
The inductance of 22 is a value obtained by connecting the inductances 16 and 17 in series. This value is selected so as to match the used band.

Next, when the voltage of the control signal 24 is at the H level, the band switching diode 14 is turned on. Since the impedance of the capacitor 15 and the diode 14 is sufficiently small in the operating frequency band of the amplifier, both ends of the inductance 17 are short-circuited. As the matching circuit 22, only the value of the inductance 16 is related to the matching.

FIG. 2C is a block diagram showing the configuration of another example of the matching circuit 22. As shown in FIG. In FIG. 2C, the resistance element 13 and the band switching diode 14 are
This is an element similar to (b). The inductance 12, the capacitor 20, and the capacitors 18 and 19
Is an element constituting.

The operation of the matching circuit 22 shown in FIG. When the voltage of the control signal 24 is at the L level, the band switching diode 14 is in the off state, and the capacitor
The impedance when the terminals of the diode 14 and the control signal 24 are viewed from the side of the capacitor 18 and the capacitor 18 is maximum. Therefore, when the value of resistance element 13 is sufficiently large, the capacity of matching circuit 22 is a value obtained by connecting capacitor 18 and capacitor 19 in series. This value is selected so as to match the used band.

When the voltage of the control signal 24 is at the H level, the band switching diode 14 is turned on. In the operating frequency band of the amplifier, both ends of the capacitor 19 are short-circuited because the impedance of the diode 14 is sufficiently small. Therefore, the capacitance of the matching circuit 22 is only the value of the capacitor 18.

In addition to the use of the band switching diode, a variable capacitance diode can be used. In this case, since the control signal 24 can use a continuous value and the variable capacitance diode can be used as a component of the resonance circuit, it is useful as a matching circuit having complicated frequency characteristics.

As described above, when a matching circuit is used, the operation of the input-side matching circuit can be switched according to the frequency band, and the operation of the input matching circuit suitable for the frequency band to be used can be selected. Can be chosen to reduce the noise figure at. As a result, it is possible to realize a low-noise amplifier in which the low-noise band is wide.

When the low-noise amplifier having such a configuration is used as a first-stage amplifier of a receiver, the overall noise figure of the receiver can be suppressed to a low level in the high-frequency band where the thermal noise is highly dependent, by the small noise figure of the amplifier. The reception sensitivity can be improved accordingly.

(Third Embodiment) A third embodiment is a radio communication apparatus constituted by the amplifier shown in FIG.
In FIG. 3, narrow band receiving bandpass filters 31 to 33 are shown.
Are connected to the changeover terminals of the changeover switches 34 and 35.
The terminal 10 is connected to the signal output terminal on the antenna side, and the amplifier 21 is connected to the output side of the filter. A broadband matching circuit (not shown) is connected to the output side of the amplifier 21. The control signal 36 is a signal for switching the connection of the filters 31 to 33.

The reception band-pass filters 31 to 33 are configured as band-pass filters having appropriate bands, and the center frequencies of the filters are sequentially different. Therefore, the filter operates as a broadband pass filter having a continuous band as a whole.

Here, three narrow-band filters are connected as an example, but the number of filters to be connected can be arbitrarily selected according to the required amplification band of the amplifier.

In general, a narrow band filter has a small amount of attenuation in a pass band. Therefore, the reception band pass filter having this configuration has a smaller pass loss and a superior out-of-band attenuation than a conventional wide band filter. It is clear. Therefore, if the filter having this configuration is used in the first stage of the receiver, the overall noise figure (NF) of the receiver can be reduced by a small amount in the high-frequency band where the thermal noise is highly dependent. The receiving sensitivity can be improved by the minute.

In the third embodiment shown in FIG.
A broadband pass filter was applied to the input side of the amplifier 21,
It may be applied to the output side or both.

(Fourth Embodiment) A fourth embodiment of the present invention is a cascade connection of the above-described first embodiment and the second embodiment. Omitted.
In this case, it is composed of a wideband antenna and a wideband low noise amplifier, and all the received wideband signals are amplified in a low noise state, which is very effective as a wideband wireless communication apparatus.

(Fifth Embodiment) A fifth embodiment of the present invention is a cascade connection of the above-described first and third embodiments. Omitted.
In this case, it is composed of a wideband antenna and a wideband amplifier, and is very effective as a wideband wireless communication device as in the fourth embodiment.

(Sixth Embodiment) A sixth embodiment of the present invention relates to a radio communication apparatus shown in FIGS. 4A, 4B and 4C. Only the part is shown. The configurations of the front-stage frequency conversion device and the rear-stage amplifier are the same as those of the conventional one, and are not shown. Each figure in FIG. 4 shows a filter used for band limitation in the intermediate frequency amplification stage. These filters have the function of reducing the signal of another channel, but within the band, and extracting only the signal of the target channel in the receiving intermediate frequency amplification stage, and are called band limiting filters or channel filters.

In FIG. 4A, the input signal terminal 10 is connected to filters 40, 41 and 42 via a changeover switch 37. The changeover switch 38 is connected to the output side of each filter,
The output of the selected filter is applied to the amplifier 21. The control signal 39 is used for synchronously driving the changeover switches 37 and 38. The band-limiting filters 40 and the like have the same center frequency and different pass-band widths.
It is assumed that the bandwidth becomes narrow in the order of 0, 41, 42. The filter 42 having the narrowest band is a filter generally called a channel filter, and has a bandwidth of one channel.

Now, suppose that the total number of channels of the wireless communication apparatus is 100, and the bandwidth of the band limiting filter 40 is 10 channels. The wireless communication device needs to find a frequency (channel) not used by others before starting communication. However, if the number of used channels is increased, a longer time is required to find an empty channel. In order to find an empty channel, it is usually performed by measuring the power of each received channel.

According to the circuit configuration of the embodiment shown in FIG. 4A, when the measurement is performed on ten channels in which the band limiting filter 40 is involved, the switches 37 and 38 are switched by the control of the control signal 39. With the filter 40 in the used state, the measurement is further performed by a power measuring device (not shown) connected to the subsequent stage in the figure. When it is determined that the ten measured channels are not used at all, the system immediately switches to the next ten channels. It performs a predetermined frequency conversion by changing the local oscillation frequency in the preceding stage (not shown),
What is necessary is just to input into the filter shown. In this way the next one
Measurement is performed for channel 0. If there is no channel to be used, input is performed for the next 10 channels. This is 10
If it is repeated ten times, the measurement of all ten channels can be performed in a short time by the operation of input switching ten times.

If it is determined that a certain 10 channels are in use, a filter 41 and a filter 42 are sequentially connected to a narrow band filter in order to specify the channel. repeat. Here, the filter 42 is a filter having the narrowest band, and after a channel can be specified, is used in a communication mode at the time of demodulation.

In FIG. 4B, the changeover switch 43,
The switch 44 is switched by the control signal 39 similarly to the changeover switches 37 and 38 in FIG. The filter 42 is shown in FIG.
This is the same as the filter 42 in FIG. Selector switch
When the positions 43 and 44 are at the positions shown in the figure, the pass band depends on the circuit system subsequent to this, that is, the pass band is wide. When the changeover switches 43 and 44 are switched to the opposite sides as shown in FIG.
This is the same as the case where only the filter 42 is used in (a), in which a narrowband signal is being received. That is, the same operation as that of FIG. 4A can be performed even in the configuration of FIG.

FIG. 4C shows a connection of a filter different from that of FIG. 4A. In FIG. 4C, the filter
The pass bandwidth and the center frequency of the filter 45 and the filter 46 have the same value. Alternatively, the center frequency may be the same, and the pass band width may be changed to be narrow or wide. With this configuration, FIG.
The operation is similar to that of FIG.

In the conventional example shown in FIG. 6, the down-converter 105 is used to convert the signal into an intermediate frequency signal. However, it is convenient if the frequency of the original high-frequency signal and the signal band are considered. For example, the configuration of this embodiment can be applied using an up-converter mixer.

When the control signal is input from the terminal 39 and the use of the intermediate filter 40 is bypassed by the changeover switch, the frequency characteristic of this circuit including the filter is not limited to the band of the filter 40, The channels on both sides outside have a sufficiently blocked characteristic, and the band used by the communication device is good. Therefore, normally, it is preferable to use in that state. When there is interference of a nearby frequency, the control signal 39 is input so that the filter 40 is connected.

(Seventh Embodiment) FIG. 5 shows a seventh embodiment of the present invention.
It is a figure showing an embodiment. In FIG. 5, a transmitter power amplifier 51 has a filter 52 connected at a front stage and a filter 53 at a rear stage, and a control signal from a control signal input terminal 54 is applied to the filter 53.

With respect to these filters, in particular, the filter 53, the same filter as that of the filter 22 in FIG. 2 may be used for the transmitter, and the description of the configuration will be omitted. In general, in power amplifiers, it is known that output matching conditions differ between a point where the output or gain of the amplifier is maximum and a point where efficiency is maximum. Considering the capacity, weight, and volume of the power battery, it is better to operate small mobile terminals such as mobile phones in terms of efficiency, but on the other hand, since the operating point is different from the point of maximum power, it is narrow. It has to be a band operation.

In this embodiment, the operation of the matching circuit 53 on the output side may be switched by inputting the control signal 54 to select a matching circuit suitable for the frequency band to be used. As a result, it is possible to realize a high power amplifier in which the band with high efficiency is wide. If the power amplifier configured as described above is used as the last-stage amplifier of the transmitter, it is possible to configure a transmitter with high efficiency over a wide band, and a wireless communication device having a long talk time, that is, a long use time.

As a device used in each of the embodiments described above, a semiconductor switch used in a band of several GHz or less is illustrated. However, when used in a microwave band or a higher frequency band, A similar effect can be obtained by using an element suitable for the frequency band, such as a circuit using a waveguide.

[0049]

As described above, according to the present invention,
It is possible to obtain a wireless communication device that has a wide band and high transmission / reception characteristics. In particular, in the case of a receiving device, the effect of being able to investigate the status of all channels in a short time is great.

[Brief description of the drawings]

FIG. 1A is a diagram illustrating a configuration of a wideband antenna according to a first embodiment of the present invention; FIG. 1B is a diagram illustrating impedance of each narrowband antenna element according to the first embodiment of the present invention; c) a diagram showing the impedance of the broadband antenna according to the first embodiment of the present invention;

FIG. 2A is a diagram showing a configuration of a wideband low noise amplifier according to a second embodiment of the present invention; FIG. 2B is an input matching circuit using the wideband low noise amplifier according to the second embodiment of the present invention; (C) a diagram illustrating an input matching circuit using a wideband low noise amplifier according to the second embodiment of the present invention;

FIG. 3 is a diagram showing a configuration of a wideband reception band limiting filter according to a third embodiment of the present invention;

4A is a diagram illustrating a configuration of a band limiting filter according to a sixth embodiment of the present invention; FIG. 4B is a diagram illustrating a configuration of a band limiting filter according to the sixth embodiment of the present invention;
(C) A diagram showing a configuration of a band limiting filter according to a sixth embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a wideband power amplifier according to a seventh embodiment of the present invention;

FIG. 6 is a block diagram illustrating a configuration of a conventional wireless communication device.

[Explanation of symbols]

 1, 2, 3, 4, 5 Narrow band antenna 6 Antenna feed point 10 Signal input terminal 11 Capacitor 12 Inductance 13 Resistive element 14 Band switching diode 15 Capacitor 16, 17 Inductance 18, 19, 20 Capacitor 21, 51 Amplifier 22, 52 Input side matching circuit 23, 53 Output side matching circuit 24, 36, 39, 54 Control signal 31, 32, 33 Reception band limiting filter 34, 35 selector switch 36 Control signal input terminal 37, 38, 43, 44, 47, 48 Selector switch 40, 41, 42, 45, 46 Band limiting filter 101 Antenna 102 Switch circuit 103 Band limiting filter 104 Low noise amplifier 105 Down converter 106 Local signal oscillator 107 Narrow band channel filter 108 Demodulator 109 Modulator 110 High power amplifier 111 Bandpass filter

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J021 AA05 AA06 DB04 FA00 FA02 FA04 FA23 FA26 FA31 HA05 JA02 5K011 DA02 DA12 DA21 DA27 EA06 5K062 AA01 AB02 AC01 AD04 AE02 AE05 BA01 BB03 BB09 BB13 BC03

Claims (7)

[Claims] 1. A wireless communication device comprising an antenna unit connected in parallel so that the characteristic impedance of each antenna as viewed from a common feed point exhibits a minimum value, at an initial stage of the communication device. 2. An amplifier input stage to which a received signal is input includes a matching circuit whose characteristics are variable by a control signal, and a broadband matching circuit is provided at an output stage of the amplifier. Wireless communication device. 3. An input stage of an amplifier to which a received signal is input includes a plurality of band-pass filters having sequentially different center frequencies, and the connection of the filter to the amplifier is switched by a control signal. A wireless communication device comprising a wideband matching circuit in an output stage of an amplifier. 4. An antenna unit connected in parallel so that the characteristic impedance of each antenna as viewed from a common feeding point exhibits a minimum value, and an amplifier to which a reception signal from the antenna unit is input, wherein the input of the amplifier is A wireless communication device comprising: a stage having a matching circuit whose characteristics are made variable by a control signal; and an amplifier having a wideband matching circuit at an output stage of the amplifier. 5. An antenna unit connected in parallel so that the characteristic impedance of each antenna as viewed from a common feeding point exhibits a minimum value, and an amplifier to which a reception signal from the antenna unit is input, wherein the input of the amplifier is The stage includes a plurality of band-pass filters having sequentially different center frequencies, and the filter is switched in connection with the amplifier by a control signal, and the output stage of the amplifier includes an amplifier including a broadband matching circuit. A wireless communication device comprising: 6. A radio communication device for converting a reception frequency to an intermediate frequency by a frequency conversion device and amplifying the intermediate frequency, wherein a band limiting filter is inserted in the intermediate frequency stage, and the filter is controlled by an external control signal. A wireless communication device having a configuration in which a pass band is variable. 7. A power amplifier to which a high-frequency signal to be transmitted is input, the input stage of the amplifier being provided with a wide-band matching circuit, and a connection to the amplifier being switched by a control signal at a subsequent stage, and a band-pass A wireless communication device comprising a plurality of band-pass filters having sequentially different center frequencies of the filters.